Pharmacological activation.
Despite the disparate results in clinical studies a few conclusions can be made. Pharmacologic activation during ECoG serves a minor role in determining the limits of a cortical excision during surgical treatment for intractable partial epilepsy. The extensive preoperative evaluation including long-term EEG monitoring to assess the electroclinical correlation and MRI are of primary importance. There is sufficient information at some epilepsy centers demonstrating a putative beneficial effect of ECoG that its continued use can be justified. Pharmacologic activation of epileptiform discharges is never preferred to spontaneous alterations occurring in the pre-excision ECoG. It would seem reasonable to consider pharmacologic activation at the time of the pre-excision ECoG if no discharges are present. Further studies will be needed to decide on the 'drug of choice', but for now methohexital would be most reasonable given the enormous amount of information regarding its induction properties. One must keep in mind the clear limitations associated with the use of these drugs especially the possibility of 'misleading' informations as documented by Fiol et al. (1990). The use of post-excision ECoG in general is sufficiently dubious that the practice of pharmacologic activation during this recording cannot be recommended. Perhaps the most reasonable view of pharmacologic activation is the position articulated by our Dr. Norman So (1995): 'There are many who advocate the injection of a short-acting barbiturate like methohexital to activate spiking during ECoG, but given the difficulty already encountered in interpreting the spontaneous ECoG it seems foolhardy to complicate the picture with potentially non-specific drug effects'.